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Nutrition Chapter 9

Functions of Water in the Body

  • Universal Solvent: Water can dissolve a wide variety of solutes, making it essential for nutrient transportation and waste removal.

  • Body Temperature Regulation: Water helps regulate temperature through perspiration (evaporation cooling mechanism).

  • Lubrication: Acts as a lubricant in joints, gastrointestinal (GI) tract (saliva, mucus), and as a cushion for the brain and spinal cord (cerebrospinal fluid).

Control Mechanisms for Water Intake and Output

  • Water Balance Regulation:

    • Hormonal Control: Antidiuretic hormone (ADH) signals kidneys to absorb more water. Aldosterone promotes sodium and water retention in kidneys.

    • Osmosis: The movement of water from areas of low solute concentration to high solute concentration through cell membranes.

Recommendations and Sources of Water

  • Recommended Intakes:

    • Adult Females: 2.7 L (~11 cups)

    • Adult Males: 3.7 L (~15 cups)

  • Sources:

    • Fruits and vegetables (over 80% water content)

    • Metabolic water produced during nutrient metabolism.

Health Consequences of Dehydration

  • Signs of Dehydration:

    • Thirst and lack of appetite at 1-2% loss of body water.

    • Increased fatigue, dizziness, headache at 4% loss.

    • Severe consequences (kidney failure, coma) at 10% loss.

Electrolytes: Essential Minerals in the Body

  • Key Electrolytes:

    • Sodium, Potassium, Chloride, and Phosphate.

  • Functions:

    • Regulate fluid balance, acid-base balance, and nerve impulse transmission.

Dietary Sources and Requirements of Electrolytes

  • Sodium: 2300 mg/day recommended. Sources include table salt, processed foods.

  • Potassium: 4700 mg/day recommended. Found in fruits, vegetables, beans, and whole grains.

  • Chloride: AI is 2300 mg/day. Found in table salt and some vegetables.

Fluid Balance Regulation and Blood Pressure Control

  • Lifestyle Modifications to Lower Blood Pressure:

    • DASH Diet: Rich in fruits, vegetables, low-fat dairy, and low in sodium and saturated fats.

    • Physical Activity: Regular aerobic exercise contributes to blood pressure management.

    • Hydration and Sodium Management: Monitor sodium intake and stay hydrated to promote vascular health.

Monitoring Hydration Status

  • Urine Color: A clear or pale yellow indicates proper hydration; dark yellow indicates dehydration.

  • Thirst: Not a reliable indicator of hydration; it's better to maintain fluid intake proactively, especially in athletes or during illness.

Risks of Overhydrogenation

  • Water Intoxication: Caused by excessive water intake diluting sodium levels leading to potential brain swelling and heart dysfunction.

Summary of Key Calcium and Other Minerals in Blood Pressure Management

  • Focus on Calcium, Magnesium, and Potassium for hypertension management; they help relax blood vessels.

  • Sodium Sensitivity: Vulnerability to high sodium leading to elevated blood pressure in some individuals.